Can you change the time on your [analog] watch on shabbat?

When you pull out the button you're stopping the electricity and cutting off the circuit.

9

Wearing the watch itself on Shabbos isn't that simple

Yes, it is, in this case.

Why is it?

My guess would be that it's an עובדא דחול or מכה בפטיש which are code words for "It's assur but I don't know why".

Is it? What if it's a wind up watch. What's wrong with stopping a circuit and cutting off electricity?

עובדא דחול --- why?

מכה בפטיש --- even if it's powered by electricity only a few poskim site מכה בפטיש as a reason. Boneh is the more popular reason. If it's a wind up it would apply at all.

What about it?

9

No Circuit

If you had a full size windup car would you be able to ride it on shabbos where there's an eiruv? My guess is if you asked your LOR he'd say no, citing Uvda dechol. I'm also guessing your LOR would asser changing a wind-up clock on shabbos for the same reason.
What are the gdarim of uvda dechol (or make bepatish)? None, really, so anything that doesn't fit anywhere but seems counterintuitive for poskim to allow is thrown there (if their gut feeling is it's assur deoraiso then MBP, if they feel derabonon then UDC)

Actually it's not that electricity is asur because of cutting off a circuit... Cutting off a circuit is asur since otherwise it wouldn't be assur to turn electric lights off (and poskim just felt it had to be asur). Whether it's binyan or make bepatish is an explanation of why it's assur after the fact.

He doesn't need to, he would assur it for the same reason bike riding (and incidentally musical instruments) are assur. Because something might break and will lead to fixing it... Not to mention that it would probably need lights, power brakes, signals etc. to be permitted on the road.


UDC is actually invoked only a handful of times AFAIK in the "traditional poskim" and was never meant as a trump card. Lately it's become popular, but if you look in the entire hilchos Shabbos in the Shulchan Aruch, you won't see it very many times. And if I remember correctly I believe that we are not mosif things under UDC. One example that I remember is yeridas hapas...

MBP is used more often, but that is an actual melacha and it still isn't used "frivolously" for the most part...